Miles in carriage, then journey on foot (5)
I believe the answer is:
tramp
'journey on foot' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Perhaps there's a link between them I don't understand?
'miles in carriage' is the wordplay.
'miles' becomes 'm' (common abbreviation).
'in' is an insertion indicator.
'carriage' becomes 'trap' (trap is a kind of carriage**).
'm' put into 'trap' is 'TRAMP'.
'then' is the link.
Can you help me to learn more?
(Other definitions for tramp that I've seen before include "Walk heavily, as when weary, or through mud" , "sometimes harboured?" , "Disreputable wanderer" , "Traveller" , "Take a walk" .)